Hyperprolactinemia is associated with incubation behavior and ovarian regression in birds. To investigate the association of prolactin (PRL), vasoactive intestinal peptide (VIP), and dopamine (DA) with the neuroendocrine regulation of incubation behavior, changes in the number of visible VIP-immunoreactive (VIP-ir) neurons in the nucleus inferioris hypothalami (IH) and nucleus infundibuli hypothalami (IN) and tyrosine hydroxylase-immunoreactive (TH-ir) neurons in the nucleus intramedialis (nI) and nucleus mamillaris lateralis (ML) of incubating native Thai hens were compared with those of nest-deprived hens. TH was used as a marker for dopaminergic (DAergic) neurons. Blood samples were collected to determine PRL levels. The localization and the number of visible VIP-ir and TH-ir neurons were determined by immunohistochemistry. Disruption of incubation behavior was accompanied by a precipitous decline in plasma PRL levels. The number of visible VIP-ir neurons in the IH-IN and TH-ir neurons in the nI and ML were high during incubation and decreased when hens were deprived of their nests. This study indicated an association between VIP neurons in the IH-IN and DA neurons in the nI and ML with the degree of hyperprolactinemia, suggesting that the expression of incubation behavior in birds might be, in part, regulated by the DAergic input from the nI and ML to VIP neurons in the IH-IN and subsequent PRL release.
Bibliographical noteFunding Information:
The authors acknowledge the financial support from the Thailand Research Fund (TRF) through the Royal Golden Jubilee (RGJ) Ph.D. Program (Grant No. PHD/0176/2547 to N.P. and Y.C.), the TRF (Grant No. RSA4780001 to Y.C.), and the National Research Council of Thailand to Y.C. The authors thank Dr. John Buntin for helpful comments and scientific discussions. The authors would like to thank the University Farm of Suranaree University of Technology for providing the chicken barns.
- Incubation behavior
- Native Thai chicken
- Nest deprivation
- Vasoactive intestinal peptide